1) Field of the Invention
This invention relates to a multivoltage power supply and also to a method for controlling the same.
2. Description of the Related Art
A multivoltage power supply has an ever-increasing importance as a power supply for various electronic equipment, because recent electronic equipment is increasingly sophisticated in its functions and, even if they externally look as a single product or unit, they are internally a combination of plural units which require different voltages.
One example of such multivoltage power supply is disclosed in Japanese Patent Application Laid-Open (Kokai) No. SHO 64-12862. This multivoltage power supply converts each output voltage into a digital signal by an A/D converter and, depending on whether the digital value is greater or smaller than a value corresponding to a desired output voltage, the amount of power to be input to the power supply is controlled to maintain constant the value of the output voltage.
Such a multivoltage power supply requires a plurality of A/D converters to output a like plural number of output voltages. This has led to the need for a large circuit, thereby preventing a dimensional reduction of the power supply and causing an increase in the manufacturing cost of the power supply.